At Limits Of Science, 9/11 ID Effort Comes to End

By ERIC LIPTON

Published: April 3, 2005

Again and again, the standard DNA tests came up negative on a three-inch-by-two-inch piece of muscle recovered from the World Trade Center site, and just a year after the 2001 attacks, forensics experts were stymied. Yet now, the scrap has been linked to a firefighter from Midtown Manhattan, allowing his death to be confirmed and giving his wife and two children some sense of finality.

Solving brutally difficult cases like that one required an investment of two extra years and millions of dollars by the medical examiner's office in New York, which sought out and used DNA identification technologies that had never been tried.

That labor -- which is coming to a close, at least for now -- is why families of victims of the 2001 attacks are gathering in New York today for an interfaith service where they plan to thank the chief medical examiner, Dr. Charles S. Hirsch, and his staff.

But as it turns out, the identification of the firefighter is one of relatively few that resulted from this extra effort to push beyond the limits of traditional DNA testing.

So far, 58 percent of the victims of the trade center attack -- 1,592 -- have been identified. But only about 111 were positively identified during what staff members at the medical examiner's office agree was an excruciatingly difficult and at times frustrating two years when it tried the new testing methods.

''We were looking at thousands of different bits of information and continually going down dead ends, and often not coming up with the answers we needed,'' said Dr. Robert C. Shaler, the office's forensic biologist, who led the effort.

Given the extraordinary violence of the towers' collapse and the relentless fires that burned for months afterward at ground zero, nearly everyone involved -- from city officials to the families to the scientists laboring over only the tiniest scraps of remains -- considers the identification effort a major achievement.

Because of the trial and exposure they received in New York, the new techniques are already in use in other places around the world, including Thailand, as part of the effort to identify tsunami victims, and Texas, for a missing-persons project.

But the work in New York has also served to demonstrate just how hard it is, however intense the determination or high-profile the job, to ignore scientific barriers and apply brand-new technologies.

''Our attitude was, if we need the technology we are going to make it happen,'' said Thomas Brondolo, deputy commissioner in the medical examiner's office. ''That same kind of attitude is what got them to clean up ground zero so quickly. But when you get to the science side, it gets much more difficult. I don't think any of us appreciated at the time what we were up against.''

What they faced was more than a dozen refrigerated tractor-trailers filled with human remains that had been pounded or burned into bits far too tiny or degraded to yield to standard DNA tests and more traditional means of identification, like dental records or fingerprints.

The medical examiner pinned his hopes mainly on two new technologies that had been under development for a few years but never used in forensic investigations.

One, known as mini short tandem repeats, or mini S.T.R.'s, was developed by John Butler, a research chemist at the National Institute of Standards and Technology in Gaithersburg, Md. The other, called single nucleotide polymorphism analysis, or SNP's, was created by Orchid BioSciences, of Princeton, N.J.

Both methods require far smaller intact pieces of DNA than the so-called S.T.R., the standard process used globally for everything from crime investigations to paternity tests, as well as the first round of DNA tests conducted on most of the 19,915 body parts collected from the trade center site. (There were 2,749 victims, according to the medical examiner's count.)

When the city began to try the two new approaches in 2002, about 1,000 of the dead had been officially identified. Dr. Shaler predicted that within a year or so he might have another 1,000 new identifications.

''It was a guess, a pure guess from hope,'' he recalled in an interview on Thursday.

Then reality set in.

From each collected bit of remains, three rectangular plates of DNA samples -- each with 96 eyedrop-size wells in them -- had been preserved at the medical examiner's office and then frozen at minus 80 degrees Fahrenheit. But frequently, when the staff sent the microscopic samples out for standard testing, the results came back incomplete.

Dr. Shaler and his staff could not say for sure whether this was because the DNA had been damaged by the effects of the attack, or simply because there was not enough genetic material remaining after previous tests.

Fearing that the inconsistencies might lead to errors, the State Health Department would not certify the SNP's procedure. But Dr. Shaler pushed on, sending his own staff to Orchid offices in Texas to inspect their protocols and approve the test.

''There was nothing wrong with the data that would lead us to believe we would get mismatches,'' he said. ''And that was what matters.''